Field of the Invention
The invention relates to a semiconductor device and a method of fabricating the same, and more particularly, the invention relates to a memory device and a method of fabricating the same.
Description of Related Art
Non-volatile memory is characterized by maintaining the stored data even when the power is down, and has thus become a mandatory device in many electronic products for providing normal operation of the electronic products. In particular, flash memory is a type of the non-volatile memory that allows multiple times of data writing, reading and erasing operations. With these advantages, the flash memory has become one of the most widely adopted memory devices for personal computers and electronic equipments.
With increases in integration of the devices, the device is also continuously scaled down. However, not every component in the flash memory can be continuously reduced but to be maintained at a specific size. For instance, during fabrication of the flash memory, sizes of source rails and source contacts are fabricated to be greater than sizes of bit lines and drain contacts, so as to reduce sheet resistance. However, by adopting such method, a layout of the word lines can be complex because the word lines need to be designed in bent-shape for passing through the source rails, which results in that a photomask must also be redesigned to take in consideration of complex optical proximity correction issues. Therefore, a cost for the photomask is significantly high. Moreover, a processing allowance thereof also quite small and prone to problems such as non-uniformity.